Modulation-Assisted Machining tool holder assemblies and methods for use in machining processes are known in the art and can improve machining performance. An example of a modulation assisted machining tool holder is shown in Mann et al., U.S. Pat. No. 7,587,965—Tool Holder Assembly and Method for Modulation-Assisted Machining. Such a device can also create machined chips with controlled size and shape, as described in Mann et al., U.S. Pat. No. 7,628,099—Machining Method to Controllably Product Chips with Determinable Shapes and Sizes. Modulation-assisted machining systems superimpose a controlled oscillation onto conventional machining processes—for example, turning, boring, drilling, trepanning, parting, or grooving.
The method of modulation-assisted machining creates an intermittent separation (gap) between the tool and the work piece, altering the mechanics of the machining process as described in Mann et al., U.S. Pat. Nos. 7,587,965 and 7,628,099. The modulation can be composed of two principal orientations of oscillation: (1) in the direction of the cutting velocity (velocity-direction modulation) or (2) in the direction of the undeformed chip thickness (feed-direction modulation). Then, the modulation can be effected in either of these principal orientations or in an orientation that is a combination of these principal orientations.
Additionally, the application of appropriate modulation conditions in the principal feed direction has the unique attribute of dividing the removed materials into a series of discrete cutting events, since the undeformed chip thickness reaches a value less than or equal to zero during each cycle of modulation. Application of appropriate modulation conditions in the principal cutting velocity direction causes the instantaneous cutting velocity to become less than or equal to zero.
Regardless of the orientation of modulation, if the modulation conditions are effective, the cutting process is intermittently interrupted during each cycle of the modulation. This interruption can have a number of important benefits for the machining process, including chip control, enhanced effectiveness of cutting fluids, reduced cutting tool wear rates, and reduction in cutting temperatures.
However, the systems and methods described in U.S. Pat. Nos. 7,587,965 and 7,628,099 are effectively limited to a stationary orientation of the tool holder assembly and interconnected components, such that the workpiece rotates while the tool remains stationary. While a stationary tool and rotating workpiece assembly can be useful in some machining situations, certain machining scenarios benefit greatly from an assembly capable of tool rotation during the machining process rather than (or in addition to) workpiece rotation. For example, it is likely far easier to use a rotating tool assembly to perform a drilling operation on a large work piece (e.g. transmission casing) than to rotate a large work piece. These rotating tools are often associated with a computer controlled machining center. A rotating tool poses major design and engineering challenges to provide the proper electrical power and/or control signals to the rotating linear actuator of the modulation tool holder assembly.
Prior art has described possible methods of wireless power using telemetry. See DE10343682 (A1), ASCHENBACH Bernd (author), Mechatronisches Werkzeugsystem zur Fräs und Bohrungsbearbeitung [Mechatronic tool system for milling and boring operations.] The prior art has also described other non-contact inductive power methods. See, J. Pi and X. P, Xu, “Design of Integration Tool-Holder System for Ultrasonic Vibration Machining Using Contactless Inductive Power Transfer”, Advanced Materials Research, Vol. 69-70 (2009) pp 520-524.
However, these methods may not be practical for implementation. Further, these methods may not resolve important aspects of the power signal levels, signal quality, and/or feed-back to the external power source of the computer controls of the parent machine tool itself.
Another difficulty faced in the design and engineering of a rotating tool assembly is dealing effectively with machining environments that often include cutting fluids (e.g., oils) and material contaminants that are used and produced during machining processes.
Thus, difficult design and engineering challenges are posed when trying to create a device that will provide simultaneous rotation to the tool holder assembly, while isolating such power and control systems (including the additional linear actuator used in modulation-assisted machining), from high-pressure cutting fluids during the machining operation. To date, the practical commercial implementation of these alternative methods discussed in Pi and Xu; and in DE20031043682 for control of modulation tool holders has not been realized.
One object of the present invention is to provide a device that addresses these needs.